Abstract

Objective

To assess the accuracy of endoscopic ultrasonography (EUS) and endoscopic retrograde
cholangiography (ERC) in patients with suspected common bile duct lithiasis.

Design

Blinded comparison of EUS and ERC with endoscopic sphincterotomy.

Setting

Endoscopy unit of a hospital in France.

Patients

121 patients (mean age 70, 57% women) who had suspected choledocholithiasis and were
likely to require endoscopic treatment. Patients who were < 50 years old and had
not had cholecystectomy were excluded.

Description of Tests and Diagnostic Standard

EUS was done (GIF-EUM20 endoscope, Olympus, Japan, 7.5 and 12.0 MHz working frequencies);
then ERC was done (TJF 100 videoduodenoscope, Olympus) immediately after. The observations
from both procedures were recorded on a standard form by an assistant. The diagnostic
standard was endoscopic sphincterotomy and instrumental exploration of the common
bile duct. The EUS and ERC operators were unaware of each others' findings.

Main Outcome Measures

Sensitivity, specificity, positive predictive value (PPV), negative predictive value
(NPV), and likelihood ratios of EUS and ERC. An analysis of some cost implications
of EUS was also done.

Main Results

Endoscopic sphincterotomy detected stones in 78 patients (66%). Test characteristics
for EUS and ERC are displayed in Table. The results of EUS and ERC showed agreement
for the presence or absence of stones in 113 patients (95%) (95% CI 89% to 98%) and
showed disagreement for 6 patients. Management with EUS done first, with ERC and sphincterotomy
done only if choledocholithiasis was confirmed by EUS, was compared with 2 other management
options where ERC was done first. EUS done as the initial test was associated with
higher costs than were the other 2 options (12% to 20%) but with lower morbidity and
fewer untreated stones.

Conclusion

Endoscopic ultrasonography was approximately as sensitive and specific as endoscopic
retrograde cholangiography for the detection of common bile duct stones and could
prevent unnecessary invasive interventions.

Commentary

A sensitive and noninvasive method of detecting gallstones in the common duct would
be very useful. Percutaneous ultrasonography, which is noninvasive, is helpful if
positive, but a negative test result cannot rule out a bile duct stone because the
test has limited sensitivity. ERC is invasive and is associated with morbidity such
as pancreatitis and cholangitis in 3% to 5% of patients (1). Sphincterotomy is associated with morbidity in 8% to 10% of patients (2). The procedure-related mortality may be as high as 1% (3, 4).

In Prat and colleagues' evaluation of EUS—an endoscopic procedure that is less invasive
and associated with less morbidity than is ERC—the sensitivity was similar to ERC.
The strength of this study is that both procedures were done independently in the
same patients. A few patients with common duct stones were missed by both tests so
that 4 of the 5 false-negative results with EUS were also negative with ERC; stones
were found only when sphincterotomy was done because a high clinical index of suspicion
existed. Thus, no available test, even ERC, is perfectly sensitive for common duct
stones. The authors conclude that EUS was as sensitive and specific as ERC for the
detection of common duct stones and that the use of EUS could avert the need for some
invasive diagnostic ERCs.

In selected patients who have suspected common duct stones, a cost analysis suggests
that an EUS-first management option has a slightly higher cost but is associated with
less morbidity. It would be interesting to consider, perhaps with decision-analysis
modeling, what the expected rates of various complications might be for different
strategies.

EUS is likely to become a valuable diagnostic tool for deciding who among selected
patients needs invasive ERC.

David F. Ransohoff, MDUniversity of North CarolinaChapel Hill, North Carolina, USA

Updated Commentary

Several newer studies (5, 6) have supported the finding that EUS and ERC have similar sensitivity for detecing
gallstones in the common duct. Using a costing model based in the United States, the
EUS-based strategy was less expensive for patients with moderate-, intermediate-,
and low-risk choledocholithiasis (5).